Research Of Tunable Erbium Doped Ring Fiber Laser

Tunable fiber lasers are ideal light sources in future optical communication systems due to their unique advantages, such as tunability, perfectly matched to fiber systems, high efficiency, and so on. Widely tunable narrow linewidth fiber lasers have many important potential applications in WDM optical networks and high-speed fiber communication systems, and have become a hot research area in the field of fiber optics.In this thesis, a novel tunable fiber laser structure was proposed by employing ring-cavity and combined widely tunable optical filters in cavity. The properties of both the combined optical filters and the tunable Erbium doped fiber ring lasers were theoretically and numerically studied in details by establishing a dynamic time domain model and a frequency domain model. The major work is as follow:1. The principle and the formulation systems of fiber lasers were introduced, and a time-domain dynamic model and a spectral-domain model were established based on the optical-field traveling-wave rate equations and extended transfer matrix methods.2. The optical properties of various optical comb filters were analyzed, such as the Hi-Bi fiber Sagnac Loops, sampled fiber Bragg gratings, and Fabry-Perot filters, Based on which, some combined widely tunable optical filters are discussed and added to the fiber ring lasers to achieve tunable function through adjusting filter parameters.3. A one-dimensional dynamic numerical model for the tunable Erbium doped fiber ring lasers was established using time-domain split-step traveling-wave method. Both the dynamic and static state characteristics of the tunable fiber lasers were simulated, including the spatial hole-burning effects, the time-domain characteristics of the output power, and the relation between the output power and the pump power.4. The threshold condition and output spectral properties of the tunable fiber lasers were studied by calculating the output power at different wavelengths through the numerical simulation in the time domain. Simultaneously, we set up a spectrum model with the upper-level particle concentration and the optical-field traveling-wav equations in the time domain, and more detailed output spectra of the laser have been obtained.